Eva S. Lončar

A Review on Kombucha Tea—Microbiology, Composition, Fermentation, Beneficial Effects, Toxicity, and Tea Fungus

Fermentation of sugared tea with a symbiotic culture of acetic acid bacteria and yeast (tea fungus) yields kombucha tea which is consumed worldwide for its refreshing and beneficial properties on human health. Important progress has been made in the past decade concerning research findings on kombucha tea and reports claiming that drinking kombucha can prevent various types of cancer and cardiovascular diseases, promote liver functions, and stimulate the immune system. Considering the widespread reports on kombucha, we recognized the need to review and update the research conducted in relation to kombucha tea, its products and tea fungus. Existing reports have suggested that the protective effects of kombucha tea are as good as those of black tea, however, more studies on kombucha tea and its composition are needed before final conclusions can be made.

Biosynthesis of glucuronic acid by means of tea fungus.

Tea fungus is the symbiosis of several acetic bacteria and some yeasts [1–3]. If tea fungus is cultivated according to the standard recipe on black tea, sweetened with sucrose, it turns this substrate into a refreshing beverage called tea fungus beverage with high nutritive value and medicinal properties. The components of tea fungus beverage are as follows: ethanol, gluconic, L-lactic, acetic acid [3–6], tartaric, succinic, malic, citric, oxalic and pyruvic acid, purines, pigments, lipids and coffeine [7], amino acids and biogenic amines [8], monosaccharides and proteins [1], enzymes [7–9], vitamins of B group and vitamin C [7, 10–11], antibiotically active substances [12, 13], usnic acid [14], carbon(IV)-oxide as well as insufficiently known products of yeasts and bacteria metabolism. Medicinal properties of tea fungus are reviewed in many references, particularely those of Russian authors [2, 12]. In the course of metabolic activities, tea fungus decomposes enzymatically sucrose into glucose and fructose. Yeasts fermented sucrose, glucose and fructose into ethanol. Acetic bacteria turn glucose, beside other acids, into gluconic acid, while fructose is never turned into this acid [15]. One of the possible ways of glucose transformation is also its oxidation into glucuronic acid at C-6, significant due to its detoxifying effects. Glucuronic acid in human liver binds the toxines making them watersoluble and, therefore, easier for elimination. UDP glucuronic acid, which is the active form of glucuronic acid, was detected in some bacteria [16]. Taking into account the fact that metabolic processes in cognate organisms are generally similar, the presence of UDP glucuronic acid is expected in tea fungus bacteria, too. Glucuronic acid is cited as tea fungus metabolite [6, 14], but without quantitative analyses. The aim of this investigation was to find out whether the culture of tea fungus, cultivated in our laboratory, on substrates with different sucrose concentration produces glucuronic acid. The influence of different concentrations of sucrose, i. e. glucose obtained by enzymatically hydrolysed sucrose, on the production of glucuronic acid was studied as it is known that glucose is a precursor in glucuronic acid biosynthesis [17].

Sequence polymorphism of the mitochondrial DNA control region in the population of Vojvodina Province, Serbia

In order to generate and establish the database for forensic identification purposes in Vojvodina Province (Serbia), the sequence of the hypervariable regions 1 (HV1) and 2 (HV2) of the mtDNA control region were determined in a population of 104 unrelated individuals from Vojvodina Province, using a fluorescent-based capillary electrophoresis sequencing method. A total of 93 different haplotypes were found, of these 83 mtDNA types were unique, nine haplotypes were shared by two individuals and one haplotype by three individuals. The variation of mtDNA HV1 and HV2 regions was confined to 116 nucleotide positions, of which 72 were observed in the HV1 and 44 in the HV2. A statistical estimate of the results for this population showed the genetic diversity of 0.9977 and the random match probability of 1.18%. Haplogroup H was the most common haplogroup (43.3%). Haplogroups observed at intermediate levels included clusters U (13.5%), T (10.6%), J (8.6%) and W (5.8%).

Chemometric estimation of the RP TLC retention behaviour of some estrane derivatives by using multivariate regression methods

AbstractQuantitative structure-retention relationship (QSRR) was developed for a series of estrane derivatives, on the basis of their retention data, obtained in reversed-phase thin-layer chromatography (RP TLC), and in silico molecular descriptors. Physicochemical and topological descriptors, as well as molecular bulkiness descriptors, were calculated from the optimized molecular structures. Full geometry optimization was achieved by using Austin Model 1 (AM1) semi-empirical molecular orbital method. In the present study, QSRR analysis was based on principal component analysis (PCA), multiple linear regression (MLR) and partial least squares (PLS) method. PCA was applied in order to reveal similarities or dissimilarities between analytes, and MLR and PLS regression methods were carried out in order to identify the most important in silico molecular descriptors and quantify their influence on the retention behaviour of studied compounds. Physically meaningful and statistically significant structure-retention relationships were established.

Assessment of Chromatographic Lipophilicity of Some Anhydro-D-Aldose Derivatives on Different Stationary Phases by QSRR Approach

This study is based on the analysis of the retention behavior of some anhydro-D-aldose derivatives in reversed-phase thin-layer chromatography (RP-TLC). Chromatographic separations were achieved applying a methanol/water mobile phase and three different stationary phases: C18-bonded silica gel, silica gel impregnated with paraffin oil, and silica gel impregnated with squalane. Retention behavior of the analyzed molecules was defined by constant and correlated with in silico molecular descriptors. According to the statistical validation parameters, obtained results showed that the established multiple-linear quantitative structure-retention relationship models (MLR-QSRR) can successfully predict the chromatographic lipophilicity of structurally similar compounds. In the present study the influence of some functional groups on the total lipophilicity of studied derivatives was determined as well. Principal component analysis (PCA) was applied in order to obtain an overview of similarity or dissimilarity among the analyzed compounds and hierarchical cluster analysis (HCA) was applied in order to compare separation characteristics of the applied stationary phases.

Effect of sucrose concentration on the products of Kombucha fermentation on molasses

Fermentation of 1.5g/l of Indian black tea, sweetened with adequate quantities of molasses (containing approx. 70g/l, 50g/l and 35g/l of sucrose), was conducted using domestic Kombucha. Inoculation was performed with 10% of fermentation broth from a previous process. The fermentation in cylindrical vessels containing 2l of liquid phase, was carried out at 22±1°C for 14 days, with periodical sampling, to measure pH, content of acids (total, acetic and l-lactic), content of remaining sucrose, and the yield of biomass at the end of fermentation. A product with 70g/l sucrose from molasses corresponds to an optimal concentration of carbon source, which provided metabolites with high pH, a low content of less desired acetic acid, a high content of highly desired l-lactic acid, an acceptable content of total acids and the highest possible level of utilisation of sucrose.

TLC ANALYSIS OF SOME PHENOLIC COMPOUNDS IN KOMBUCHA BEVERAGE

Black and green tea contains a wide range of natural phenolic compounds Flavanoids and their glycosides, catechins and the products of their condensation, and phenolic acids are the most important. Kombucha beverage is obtained by fermentation of tea fungus on black or green tea sweetened with sucrose. The aim of this paper was to investigate the composition of some phenolic compounds, catechin, epicatechin, quercetin, myricetin, gallic and tanic acid, and monitoring of their status during tea fungus fermentation. The method used for this study was thin layer chromatography with two different systems. The main phenolic compounds in the samples with green tea were catechin and epicatechin, and in the samples with black tea it was quercetin.

Reversed-phase thin-layer chromatography behavior of aldopentose derivatives

Quantitative structure-retention relationships (QSRR) have been used to study the chromatographic behavior of some aldopentose. The behavior of aldopentose derivatives was investigated by means of reversed-phase thin-layer chromatography (RP TLC) on silica gel impregnated with paraffin oil stationary phases. Binary mixtures of methanol-water, acetone- water and dioxane-water were used as mobile phases. Retention factors, RM 0, corresponding to zero percent organic modifier in the aqueous mobile phase was determined. Lipophilicity, C0, was calculated as the ratio of the intercept and slope values. There was satisfactory correlation between them and log P values calculated using different theoretical procedures. Some of these correlations offer very good predicting models, which are important for a better understanding of the relationships between chemical structure and retention. The study showed that the hydrophobic parameters RM 0 and C0 can be used as a measures of lipophilicity of investigated compounds.

Structure-Retention Analysis of Some 1,6-anhydrohexose and D-aldopentose Derivatives by Linear Multivariate Approach

Quantitative structure-retention relationships (QSRR) was developed for eleven 1,6-anhydrohexose and D-aldopentose derivatives using their retention data (RM0 values), obtained by normal phase (NP) thin-layer chromatography (TLC) and partition coefficients for n-octanol/water bi-phase system–logP. In order to select molecular descriptors that best describe the retention behavior of the investigated molecules, principal component analysis (PCA) was carried out, followed by hierarchical cluster analysis (HCA) and multiple linear regression (MLR). The best QSRR models were validated by leave-one-out technique and by the calculation of statistical parameters. Established mathematical models are meaningful and statistically significant and can successfully predict retention behavior of investigated 1,6-anhydrohexose and D-aldopentose derivatives.

Chemometric approach to texture profile analysis of kombucha fermented milk products

In the present work, relationships between the textural characteristics of fermented milk products obtained by kombucha inoculums with various teas were investigated by using chemometric analysis. The presented data which describe numerically the textural characteristics (firmness, consistency, cohesiveness and index of viscosity) were analysed. The quadratic correlation was determined between the textural characteristics of fermented milk products obtained at fermentation temperatures of 40 and 43 °C, using milk with 0.8, 1.6 and 2.8% milk fat and kombucha inoculums cultivated on the extracts of peppermint, stinging nettle, wild thyme and winter savory. Hierarchical cluster analysis (HCA) was performed to identify the similarities among the fermented products. The best mathematical models predicting the textural characteristics of investigated samples were developed. The results of this study indicate that textural characteristics of sample based on winter savory have a significant effect on textural characteristics of samples based on peppermint, stinging nettle and wild thyme, which can be very useful in the determination of products texture profile.